What are the considerations for using finasteride (Finasteride) in patients with impaired renal function, specifically stage 3 kidney disease (Chronic Kidney Disease, CKD)?

From the Guidelines

Finasteride can generally be used safely in patients with stage 3 chronic kidney disease without dose adjustments. Since finasteride is extensively metabolized by the liver with minimal renal excretion, impaired kidney function typically does not significantly affect its clearance or increase risk of toxicity 1. The standard dosing remains 1 mg daily for male pattern baldness or 5 mg daily for benign prostatic hyperplasia. Patients with CKD stage 3 should still be monitored for the usual side effects of finasteride, including sexual dysfunction, decreased libido, and rarely depression.

Key Considerations

• Finasteride is contraindicated in women who are or may become pregnant due to risks of fetal abnormalities.
• Regular monitoring of kidney function is still recommended as part of routine care for these patients.
• The medication's favorable pharmacokinetic profile makes it a reasonable option for CKD patients who require treatment for androgenetic alopecia or prostatic hyperplasia.
• According to the national kidney foundation practice guidelines for chronic kidney disease, patients with stage 3 chronic kidney disease should be evaluated and treated for complications of decreased GFR, such as anemia, malnutrition, bone disease, neuropathy, and decreased quality of life 1.

Monitoring and Referral

• Patients with CKD stage 3 should be referred to a specialist for consultation and comanagement if the patient's personal physician cannot adequately evaluate and treat the patient.
• A nephrologist should participate in the care of patients with a GFR less than 30 mL/min per 1.73 m2 (level B recommendation) 1.

From the FDA Drug Label

In patients with chronic renal impairment, with creatinine clearances ranging from 9.0 to 55 mL/min, AUC, maximum plasma concentration, half-life, and protein binding after a single dose of 14C-finasteride were similar to values obtained in healthy volunteers. No dosage adjustment is necessary in patients with renal impairment.

Key Considerations:

• No dosage adjustment is necessary for patients with renal impairment, including those with stage 3 kidney disease.
• Finasteride pharmacokinetics in patients with chronic renal impairment were similar to those in healthy volunteers.
• However, urinary excretion of metabolites was decreased in patients with renal impairment, leading to an increase in fecal excretion of metabolites and higher plasma concentrations of metabolites. 2

From the Research

Considerations for Using Finasteride in Stage 3 Kidney Disease

• The use of finasteride in patients with impaired renal function, specifically stage 3 kidney disease, requires careful consideration of the potential effects on renal morphology and function 3.
• Studies have shown that finasteride can cause morphological and functional damages in rat kidneys, including reduced kidney weight, kidney volume, cortical volume, glomerular volumetric density, and mean glomerular volume 3.
• The estimated glomerular filtration rate (eGFR) is a crucial factor in assessing renal function, and various equations, such as the Modification of Diet in Renal Disease (MDRD) equation and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, can be used to estimate eGFR 4, 5, 6, 7.
• However, these equations may have limitations and biases, particularly in patients with normal baseline GFR or in those with chronic kidney disease (CKD) 5, 6.
• The MDRD equation, for example, has been shown to systematically underestimate GFR in healthy persons and may not be accurate in patients with CKD 6.
• A new equation developed with patients who have CKD and healthy persons may be a step toward accurately estimating GFR when the diagnosis of CKD is unknown 6.
• In patients with stage 3 kidney disease, it is essential to monitor renal function closely and adjust the finasteride dosage accordingly to minimize potential adverse effects on the kidneys 3.
• Further studies are needed to fully understand the impact of finasteride on renal function in patients with CKD and to develop more accurate equations for estimating eGFR in this population.